oritavancin, sold under the brand name orbactiv, is a novel semisynthetic glycopeptide antibiotic medication for the treatment of serious gram-positive bacterial infections. its chemical structure as a lipoglycopeptide is similar to vancomycin. 
 
the u.s. food and drug administration (fda) and the european medicines agency (ema) have approved oritavancin for treatment of acute bacterial skin and skin structure infections. 
 
in vitro activity 
oritavancin shares certain properties with other members of the glycopeptide class of antibiotics, which includes vancomycin, the current standard of care for serious gram-positive infections in the united states and europe. it possesses potent and rapid bactericidal activity in vitro against a broad spectrum of both resistant and susceptible gram-positive bacteria, including staphylococcus aureus, mrsa, enterococci, and streptococci. oritavancin was more active than either metronidazole or vancomycin against strains of clostridium difficile tested. 
 
oritavancin has potential use as a therapy for exposure to bacillus anthracis, the gram-positive bacterium that causes anthrax, having demonstrated efficacy in a mouse model both before and after exposure to the bacterium. 
 
mechanism 
the 4'-chlorobiphenylmethyl group disrupts the cell membrane of gram-positive bacteria. it also acts by inhibition of transglycosylation and inhibition of transpeptidation.